Electrowetting display device

ABSTRACT

An electrowetting display device includes a first base substrate, a plurality of first electrodes disposed on the first base substrate and positioned to respectively correspond to positions of a plurality of pixels, a partition wall disposed on the first base substrate to partition the pixels, a second electrode disposed on the partition wall and including a plurality of openings, a second base substrate facing the first base substrate, and an electrowetting layer disposed between the first base substrate and the second base substrate, the electrowetting layer respectively being moved by voltages respectively applied to the first electrode and the second electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority under 35U.S.C. §119 of Korean Patent Application No. 10-2012-0050425, filed onMay 11, 2012, the contents of which are hereby incorporated byreference.

BACKGROUND

1. Field of Disclosure

The present disclosure relates to an electrowetting display device. Moreparticularly, the present disclosure relates to an electrowettingdisplay device capable of improving transmittance.

2. Description of the Related Art

Recently, various display devices, such as a liquid crystal display, anorganic light emitting diode, an electrowetting display device, a plasmadisplay panel, electrophoretic display device, etc., have beendeveloped.

Among these, the electrowetting display device has been spotlighted as anext generation display device because the electrowetting display devicehas various properties, e.g., low power consumption, fast responsespeed, high visibility, etc., when compared to the liquid crystaldisplay.

In general, electrowetting display devices are classified intotransmission type electrowetting display devices and reflection typeelectrowetting display devices. Electrowetting display devices generallyinclude a first substrate, a second substrate facing the firstsubstrate, and an electrowetting layer disposed between the first andsecond substrates. The first substrate includes a plurality of pixelelectrodes respectively corresponding to a plurality of pixels, and thesecond substrate includes a common electrode formed in a single body.The reflection type electrowetting display device further includes areflective layer to reflect light. Movement of the electrowetting layeris controlled by voltages respectively applied to first and secondelectrodes of the electrowetting display device, and thus an image isdisplayed in the electrowetting display device.

In the transmission electrowetting display device, the light passesthrough the second substrate after passing through the first substrateand the electrowetting layer. In the reflection electrowetting displaydevice, the light passing through the first substrate and theelectrowetting layer is reflected by a reflective layer, and thereflected light passes through the first substrate again. Accordingly,light passes through the first substrate once in the case of thetransmission type electrowetting display device and passes through thefirst substrate twice in the case of the reflection type electrowettingdisplay device.

An improvement of the electrowetting display device is required.

SUMMARY

The present disclosure provides an electrowetting display device capableof improving transmittance.

An electrowetting display device includes a first base substrate, aplurality of first electrodes disposed on the first base substrate eachpositioned to correspond, respectively, to a position of one of aplurality of pixels, a partition wall disposed on the first basesubstrate to partition the pixels, a second electrode disposed on thepartition wall and including a plurality of openings, a second basesubstrate facing the first base substrate, and an electrowetting layerdisposed between the first base substrate, the electrowetting layerbeing moved by voltages applied to the first electrode and the secondelectrode.

The second electrode has a width between two openings adjacent to eachother equal to or smaller than a width of the partition wall between twopixels adjacent to each other.

The first base substrate includes a display area and a non-display area,the display area includes the partition wall and the second electrodedisposed on the partition wall, and the non-display area includes acommon voltage line disposed on the first base substrate and a thirdelectrode disposed on an outermost side surface of the partition wall toelectrically connect the second electrode and the common voltage line.

The non-display area further includes an insulating layer disposed onthe first base substrate to cover the common voltage line, and aconnection electrode electrically connected between the third electrodeand the common voltage line through a contact hole formed through theinsulating layer.

The third electrode has a height corresponding to a distance between anupper surface of the insulating layer and an upper surface of the secondelectrode to make contact with the second electrode.

The third electrode and the second electrode include the sametransparent conductive material.

The openings are respectively positioned correspond to the position ofthe pixels.

The pixels are arranged in n rows by m columns, and the openings of thesecond electrode respectively correspond to pixel units each includingtwo or more, but less than m, pixels arranged in each row.

The openings respectively correspond to the pixel units each includingtwo pixels arranged in each row.

The openings respectively correspond to the pixel units each includingthree pixels arranged in each row.

The openings respectively correspond to the pixel units each including mpixels arranged in each row.

The pixels are arranged in n rows by m columns, and the openings of thesecond electrode respectively correspond to pixel units each includingthe pixels arranged in two rows by two or more but m or less columns.

The openings respectively correspond to the pixel units each includingfour pixels arranged in two rows by two columns.

The openings respectively correspond to the pixel units each includingsix pixels arranged in two rows by three columns.

The openings respectively correspond to the pixel units each includingthe pixels arranged in two rows by m columns.

According to the above, the electrowetting display device may improvethe transmittance of the light.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages of the present invention will becomereadily apparent by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is a perspective view showing an electrowetting display deviceaccording to a first exemplary embodiment;

FIG. 2 is a plan view showing the electrowetting display device shown inFIG. 1;

FIGS. 3A and 3B are cross-sectional views taken along a line I-I′ shownin FIG. 2;

FIG. 4 is a cross-sectional view taken along a line II-IF shown in FIG.2;

FIG. 5 is a plan view showing an electrowetting display device accordingto a second exemplary embodiment;

FIG. 6 is a cross-sectional view showing a pixel shown in FIG. 5;

FIGS. 7A to 7C are plan views showing an electrowetting display deviceaccording to a third exemplary embodiment; and

FIGS. 8A to 8C are plan views showing an electrowetting display deviceaccording to a fourth exemplary embodiment.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments will be explained in detail withreference to the accompanying drawings.

FIG. 1 is a perspective view showing an electrowetting display deviceaccording to a first exemplary embodiment.

Referring to FIG. 1, an electrowetting display device 100 includes afirst substrate 110, a second substrate 120 facing the first substrate110, and an electrowetting layer 130 disposed between the first andsecond substrates 110 and 120.

The first substrate 110 includes a first base substrate 111, a pluralityof first electrodes 112 disposed on the first base substrate 111, aninsulating layer 113 disposed on the first base substrate 111 to coverthe first electrodes 112, a partition wall 114 disposed on theinsulating layer 113 to partition a plurality of pixels PX, and a secondelectrode 115 disposed on the partition wall 114.

The first electrodes 112 are positioned respectively to correspond tothe positions of the pixels PX and include a transparent conductivematerial, such as an indium tin oxide (ITO), a conductive polymer, acarbon nanotube (CNT), etc. The first electrodes 112 may be defined aspixel electrodes.

The insulating layer 114 is surface-treated to have a hydrophobicproperty or includes an additional hydrophobic layer (not shown) toimpart a hydrophobic property to the layer.

The partition wall 115 is formed of photoresist or formed by patterningthe insulating layer, e.g., SiNx, SiOx, etc.

The second electrode 115 is formed to make contact with an upper surfaceof the partition wall 114 and includes a plurality of openings 116positioned respectively corresponding to the positions of pixels PX.That is, the openings 116 are over the area that includes the firstelectrodes in each pixel PX. The openings 116, in which the materialused for the second electrode 115 is not formed, will be described inmore detail with reference to FIGS. 3A and 3B.

The second electrode 115 has a width corresponding to the distancebetween two openings adjacent to each other. The partition wall 114 hasa width corresponding to the distance between two pixels adjacent toeach other.

The second electrode 115 may be formed to have the same width as thepartition wall 114. That is, the second electrode 115 is patternedtogether with the partition wall 114 using the same mask used to formthe partition wall 114. The second electrode 115 is applied with acommon voltage and formed of a transparent conductive material, such asindium tin oxide (ITO). In addition, the second electrode 115 may bereferred to as a common electrode.

The pixels PX are arranged in n rows by m columns. Each of “m” and “n”is an integer number greater than zero (0). The pixels PX are configuredto include a red pixel, a green pixel, and a blue pixel. The red, green,and blue pixels are regularly repeatedly arranged in a row direction anda column direction. However, the arrangement of the pixels PX should notbe limited thereto or thereby.

The second substrate 120 includes a second base substrate 121 facing thefirst base substrate 111 and a color filter CF 122 formed on the secondbase substrate 121. The color filter CF includes a color pixelrepresenting a red, green, or blue color. In the present exemplaryembodiment, the color filter 122 is included in the second substrate120, but the color filter 122 may be included in the first substrate110.

The first and second base substrates 111 and 121 may be a transparentinsulator and formed of a polymer, e.g., glass or plastic. In the casethat the first and second base substrates 111 and 121 are plasticsubstrates, each of the first and second base substrates 111 and 121 isconfigured to include, for example, polyethylene terephthalate (PET),fiber reinforced plastic (FRP), or polyethylene naphthalate (PEN). Inaddition, when each of the first and second base substrates 111 and 121is a plastic substrate, the first and second base substrates 111 and 121may be flexible.

The electrowetting layer 130 includes a first fluid and a second fluid,which are immiscible with each other. The first fluid has electricalnon-conductivity or non-polarity and the second fluid has electricalconductivity or polarity. The movement of the electrowetting layer 130is controlled in each pixel by a gray-scale voltage applied to the firstelectrode 112 and the common voltage applied to the common electrode122, and thus a desired image is displayed through the electrowettingdisplay device 100. The operation of the pixels will be described withreference to FIGS. 3A and 3B.

In a conventional electrowetting display device in which a secondelectrode is formed having a single, uniform body on the second basesubstrate, a portion of the light incident onto the display device maynot transmit through such a second electrode. That is, transmittance oflight is lowered by the second electrode. However, in the electrowettingdisplay device 100, the second electrode 115 includes the openings 116respectively corresponding to the pixels PX and is formed on thepartition wall 114. Because the material used to form the secondelectrode 115 is not formed in the openings 116, the light passesthrough the openings 116. Accordingly, the electrowetting display device100 according to the first exemplary embodiment may improve thetransmittance of the light.

In addition, because the second electrode 115 is formed on the partitionwall 114 without being formed on the second base substrate 121, aprocess of forming the second substrate 120 may be simplified. Thesecond electrode 115 is formed to have the same width as the partitionwall 114 and is patterning together with the partition wall 14 using thesame mask. Thus, no additional mask is required when the secondelectrode 115 is formed.

FIG. 2 is a plan view showing the electrowetting display device shown inFIG. 1.

FIG. 2 shows only the plan configuration of the first substrate 110 toexplain the plan configuration of the second electrode 115 formed on thepartition wall 114.

Referring to FIG. 2, the first substrate 110 includes a display area DAand a non-display area NDA. The display area DA and the non-display areaNDA may be vertically divided. Therefore, the first base substrate 111of the first substrate 110 may include the display area DA and thenon-display area NDA.

The display area DA includes the partition wall 114 that partitions thepixels PX and the second electrode 115 disposed on the partition wall114. In detail, the partition wall 114 is disposed on the first basesubstrate 111 of the display area DA, and the second electrode 115including the openings 116 is disposed on the partition wall 114. Asdescribed above, the pixels PX partitioned by the partition wall 114 aredisposed in the display area DA. The openings 116 are positioned tocorrespond to the position of the pixels PX, respectively.

As described above, the width W1 of the second electrode 115 correspondsto the width between the two openings 116 adjacent to each other.Because the width of the partition wall 114 is equal to the width W1 ofthe second electrode, only the second electrode 115 can be seen in theplan configuration view shown in FIG. 2.

The pixels PX are partitioned by the partition wall 114, and the secondelectrode 115 has the same width as the width of the partition wall 114,and thus the width of the openings and the width of the pixels PX may bethe same, as shown in the plan configuration view.

The non-display area NDA includes a common voltage line VCOM_L disposedon the first base substrate 111 and a third electrode 117 disposed atoutermost side of the partition wall 114 to electrically connect thesecond electrode 115 and the common voltage line VCOM_L. Accordingly,the common voltage may be applied to the second electrode 115. The thirdelectrode 117 disposed at the outermost side of the partition wall 114will be described with reference to FIG. 4.

FIGS. 3A and 3B are cross-sectional views taken along a line I-I′ shownin FIG. 2.

FIGS. 3A and 3B show only one pixel, but the other pixels have the sameconfiguration as the one pixel shown.

FIG. 3A shows the electrowetting layer 130 when no voltage is applied tothe pixel PX. FIG. 3B shows the electrowetting layer 130 when voltage isapplied to the pixel PX.

Referring to FIG. 3A, a side area of the pixel PX is defined as an areabetween two dotted-lines III-III′ shown in FIG. 3A. Accordingly, thearea in which the pixel PX is formed may be overlapped by the firstsubstrate 110 and the second substrate 120 as shown in FIG. 3A. Theconfiguration of the first and second substrates 110 and 120 is asdescribed above.

The pixel PX includes the first electrode 112 disposed on the first basesubstrate 111, and a first area A between the partition wall 114 and thefirst electrode 112. The first area A is a region in which the firstelectrode 112 is not formed.

An area PX_B between the pixels PX may be defined as a pixel boundaryarea PX_B, and the partition wall 114 is formed in the pixel boundaryarea PX_B.

As described above, the width W2 of the partition wall 114 correspondsto the width between two pixels PX adjacent to each other. Thus, asshown in FIG. 3A, the width of the pixel boundary area PX_B between thetwo pixels PX adjacent to each other may be equal to the width W2 of thepartition wall 114.

The second electrode 115 is disposed on the partition wall 114 with theopenings 116. As described above, the width W1 of the second electrode115, which corresponds to the width between the openings 116 adjacent toeach other, may be equal to the width W2 of the partition wall 114.Because the second electrode 115 is formed to have the same width as thepartition wall 114, the second electrode 115 may be patterned using thesame mask as that used to form the partition wall 114. As a result, noadditional mask is needed to form the second electrode 115.

The electrowetting layer 130 disposed between the first substrate 110and the second substrate 120 includes the first fluid 131 and the secondfluid 132, which are immiscible with each other. The first fluid 131 haselectrical non-conductivity or non-polarity and the second fluid 132 haselectrical conductivity or polarity. In addition, the first fluid 131has hydrophobicity and the second fluid 132 has hydrophilicity. Forinstance, the first fluid 131 may include an organic solvent, such as,for example, silicon oil, mineral oil, carbon tetrachloride (CCL₄), etc.The second fluid 132 may include an aqueous solution and electrolyte,such as, for example, sodium chloride (NaCl).

The first fluid 131 includes a black dye or a light absorbing materialto absorb the light incident thereto. In addition, the first fluid 131is dispersed over the pixel PX or moves to a side portion of the pixelPX so as to serve as a light shutter. The second fluid 132 may betransparent, and thus the second fluid 132 may transmit the lightincident thereto.

The first fluid 131 and the second fluid 132 have different polaritiesfrom each other, and thus the first fluid 131 and the second fluid 132are immiscible with, and make contact with, each other. The first fluid131 is disposed on the insulating layer 113 in the pixel PX partitionedby the partition wall 114, and the second fluid 132 is disposed on thefirst fluid 131.

As an exemplary embodiment, the first fluid 131 includes a dyerepresenting one of red, green, and blue colors or a materialrepresenting one of red, green, and blue colors. In this case, the colorfilter CF may be removed from the electrowetting display device 100. Themovement of the electrowetting layer 130 is controlled by voltagesrespectively applied to the first electrode 112 and the second electrode115.

FIG. 3A shows a configuration of a pixel for an electrowetting displaydevice used as a transmission type display device. However, theelectrowetting display device 100 may be used as a reflection typedisplay device.

Although not shown in figures, in a case in which the electrowettingdisplay device 500 is used as a reflection type display device, theelectrowetting display device 100 may further include a reflective layerconfigured to include a reflective metal, e.g., aluminum (Al) and/oraluminum-neodymium (AlNd). The reflective layer is disposed on the firstelectrode 112 or under the first substrate 110. However, the firstelectrode 112 may include the reflective metal, such as aluminum (Al) toreflect the light. In this case, the electrowetting display device 100does not include the reflective layer.

When the gray scale voltage is not applied to the first electrode 112,the pixel PX displays a black gray scale because the first fluid 131covers the insulating layer 113 as shown in FIG. 3A.

Referring to FIG. 3B, the gray-scale voltage Vgray is applied to thefirst electrode 112, and the common voltage Vcom is applied to thesecond electrode 115. The gray-scale voltage Vgray applied to the firstelectrode 112 has a level lower than that of the common voltage Vcom. Inthis case, the common voltage Vcom may be a positive (+) polarityvoltage and the gray scale voltage Vgray may be a negative (−) polarityvoltage.

As shown in FIGS. 3A and 3B, a portion of the second fluid 132 makescontact with the second electrode 115. The second fluid 132 iselectrically conductive. Accordingly, a portion of the second fluid 132makes contact with the second electrode 115, and the common voltage Vcomis applied to the second fluid 132 through the second electrode 115.That is, the second fluid 132 disposed in the pixel PX receives thecommon voltage Vcom through the second electrode 115 formed on thepartition wall 114.

In the case that the common voltage Vcom is applied to the second fluid132 and the first electrode 112 is applied with the gray-scale voltageVgray having the lower level than the common voltage Vcom, the secondfluid 132 is polarized. For example, the first electrode 112 has thenegative (−) polarity and the area of the second fluid 132, which isadjacent to the first electrode 112, has the positive (+) polarity. Inthis case, an attractive force acts between the first electrode 112having the negative (−) polarity and the area of the second fluid 132having the positive (+) polarity. Accordingly, the polarized secondfluid 132 makes contact with the insulating layer 113, while a surfacetension of the second fluid 132 is changed by the attractive force, sothat the second fluid 132 pushes out, or displaces, the first fluid 132,which is pushed to a side portion of the pixel PX above first area A inwhich electrode 112 is not formed.

The first fluid 131 that includes the organic solvent tends to collect,or gather, instead of disperse, in fluid 132 due to the differentpolarities of the fluids 131 and 132 Accordingly, the first fluid 131 ispushed out, i.e., displaced, to the side portion of the pixel PX by thesecond fluid 132, and is stably gathered in the side portion of thepixel PX.

For instance, because the pixel electrode 112 is not formed in the firstarea A of the pixel PX shown in FIG. 3B, the gray-scale voltage Vgray isnot applied to the first area A and the electric field is not generatedin the first area A. As a result, the first fluid 131 may be displacedtowards, and collect (gather) in the area of the pixel PX, whichincludes the first area A. That is, the first fluid 131 is gathered inthe left side portion of the pixel PX. In this case, the light passesthrough the second fluid 132 now positioned above the first electrode112, and thus the pixel PX displays a predetermined image.

The amount of the first fluid 131 that is displaced depends on the leveldifference between the gray-scale voltage Vgray applied to the firstelectrode 112 and the common voltage Vcom applied to the secondelectrode 115. For instance, as the level difference between the commonvoltage Vcom and the gray-scale voltage Vgray increases, the first fluid131 is increasingly displaced toward, and gathered, in the first area A.The common voltage Vcom has a uniform voltage level, and the gray-scalevoltage corresponds to the gray scale displayed in the pixel PX. Thus,the amount of the first fluid 131 displaced may be determined by thelevel of the gray-scale voltage Vgray applied to the first electrode112.

The first fluid 131 displaced to the side portion of the pixel PX has asecond height H2. As shown in FIG. 3B, the second height H2 of the firstfluid 131 may be higher than a first height H1 corresponding to adistance between an upper surface of the insulating layer 113 and anupper surface of the second electrode 115. A side surface of thepartition wall 114 may be surface-treated using a hydrophobic materialwhile an upper surface of the second electrode 115 may besurface-treated using a hydrophilic material. Thus, although the firstfluid 131 has the second height H2 higher than the first height H1, thefirst fluid 131 has a chemical affinity to the side surface of thepartition wall 114, which is higher than a chemical affinity to theupper surface of the partition wall 114. As a result, the first fluid131 may be prevented from flowing into the adjacent pixel beyond thepartition wall 114.

As described above, although the second fluid 132 partially makescontact with the second electrode 115, the common voltage Vcom isapplied to the second fluid 132 through the second electrode 115. Thus,the pixel PX may be normally operated.

The second electrode 115 of the electrowetting display device 100includes the openings 116 respectively positioned corresponding to thepositions of the pixels PX, and second electrode 115 is disposed on thepartition wall 114. Because the material used to form the secondelectrode 115 does not exist in the openings 116, the light passesthrough the openings 116. Accordingly, the electrowetting display device100 according to the first exemplary embodiment may improve thetransmittance of the light.

In addition, because the second electrode is formed on the partitionwall 114 of the first substrate 110 without being formed on the secondbase substrate 121, the process of forming the second substrate 120 maybe simplified. In addition, the second electrode 115 is formed to havethe same width as the width of the partition wall 114, so the secondelectrode 115 is patterned by using the same mask as the partition wall114. Therefore, no additional mask is required to form the secondelectrode 115.

FIG. 4 is a cross-sectional view taken along a line II-II′ shown in FIG.2.

Referring to FIG. 4, the non-display area NDA includes the commonvoltage line VCOM_L, a connection electrode CNT, and a third electrode117.

In more detail, the common voltage line VCOM_L is disposed on the firstbase substrate 111 in the non-display area NDA to receive the commonvoltage Vcom. In addition, the insulating layer 113 is disposed on thefirst base substrate 111 to cover the common voltage line VCOM_L.

The connection electrode CNT is electrically connected to the commonvoltage line VCOM_L through a first contact hole C_H1 formed through theinsulating layer 113. The third electrode 117 is formed in thepredetermined area of the outermost side surface of the partition wall114. The outermost side surface of the partition 114 may be an outermostside surface of the display area NDA.

A lower surface of the third electrode 117 makes contact with theconnection electrode CNT, and thus the third electrode 117 iselectrically connected to the connection electrode CNT. In addition, thethird electrode 117 may have the first height H1, which is the height atwhich the second electrode 115 is formed. Accordingly, the upper sidesurface of the third electrode 117 makes contact with the side surfaceof the second electrode 115, so that the third electrode 117 iselectrically connected to the second electrode 115.

The third electrode 117 may be formed of a transparent conductivematerial, e.g., indium tin oxide, as the second electrode 115. Inaddition, the third electrode 117 may be formed of a conductive materialcontaining silver, e.g., a silver paste. In the case that the thirdelectrode 117 is formed of the silver paste, the silver paste is coatedonto the predetermined area of the outermost side surface of thepartition wall 114, in which the third electrode 117 is formed, andcured.

Due to the above-mentioned configuration, the common voltage Vcomapplied to the common voltage line VCOM_L may be applied to the secondelectrode 115 formed on the partition wall 114 through the connectionelectrode CNT and the third electrode 117.

FIG. 5 is a plan view showing an electrowetting display device accordingto a second exemplary embodiment and FIG. 6 is a cross-sectional viewshowing a pixel shown in FIG. 5.

The electrowetting display device 200 in FIGS. 5 and 6 have the sameconfiguration as that of the electrowetting display device 100 in FIGS.1 to 4 except for the width of the partition wall and the width of thesecond electrode. Accordingly, the configurations of the electrowettingdisplay device 200 that are different from the electrowetting displaydevice 100 will be mainly described.

Referring to FIGS. 5 and 6, the electrowetting display apparatus 300includes a second electrode 215 is disposed on the partition wall 214and includes openings 216 positioned corresponding to the positions ofpixels PX. The second electrode 215 has a width W1 corresponding to awidth between two openings 216 adjacent to each other. The partitionwall 214 has a width W2 corresponding to a width between two pixels PXadjacent to each other. The width W1 of the second electrode 215 may besmaller than the width W2 of the partition wall 214.

As shown in FIG. 6, a portion of the second fluid 232 makes contact withthe second electrode 215. The second fluid 232 is electricallyconductive. Accordingly, a portion of the second fluid 232 makes contactwith the second electrode 215, and the common voltage Vcom is applied tothe second fluid 232 through the second electrode 215. That is, thesecond fluid 232 disposed in the pixel PX receives the common voltageVcom through the second electrode 215 formed on the partition wall 214.

The other elements of the electrowetting display device 200 have thesame configurations as those of the electrowetting display device 100according to the first exemplary embodiment, and thus detaileddescriptions of such other elements of the electrowetting display device200 will be omitted.

The second electrode 215 of the electrowetting display device 200 isdisposed on the partition wall 214 and includes the openings 216positioned to correspond respectively to the position of the pixels PX.Because the second electrode 215 is not formed in the openings 216,light passes through the openings 216. Thus, the electrowetting displaydevice 200 may improve the transmittance of the light.

FIGS. 7A to 7C are plan views showing an electrowetting display deviceaccording to a third exemplary embodiment.

The electrowetting display device 300 according to the third exemplaryembodiment have the same configuration as that of the electrowettingdisplay device 100 according to the second exemplary embodiment exceptfor a configuration of the openings. Accordingly, the configuration ofthe openings for the electrowetting display device 300 will be mainlydescribed.

Referring to FIGS. 7A to 7C, a second electrode 315 of theelectrowetting display device 300 includes openings 316. As describedabove, the pixels PX are arranged in n rows by m columns. In addition,although not shown in FIGS. 7A to 7C, an area between the pixels PX maybe defined as a pixel boundary area. A partition wall 314 is disposed inthe pixel boundary area and the second electrode 315 is disposed on thepartition wall 314.

Each of the openings 316 is positioned to corresponds to, i.e.,surround, two or more, but less than m, pixels PX arranged in each row.That is, the second electrode 315 is disposed on the partition wall 314formed in the pixel boundary area between the pixel units each includestwo or more, but less than m, pixels PX.

In detail, as shown in FIG. 7A, the second electrode 315 is disposed onthe partition wall 314 and includes the openings 316 each of whichcorresponds to the pixel units each having two pixels PX arranged ineach row. That is, the second electrode 315 is disposed on the partitionwall 314 formed in the pixel boundary area between the pixel units eachhaving two pixels PX in each row.

In addition, as shown in FIG. 7B, the second electrode 315 may includethe openings 316 each of which corresponds to the pixel units eachhaving three pixels PX arranged in each row. That is, the secondelectrode 315 may be disposed on the partition wall 314 formed in thepixel boundary area between the pixel units each having three pixels PXin each row.

Further, as shown in FIG. 7C, the second electrode 315 may include theopenings 316 each of which corresponds to the pixel units each having mpixels PX arranged in each row. That is, the second electrode 315 may bedisposed on the partition wall 314 formed in the pixel boundary areabetween the pixel units each having m pixels PX in each row. Thestructure shown in FIG. 7C may be called a stripe structure.

Although not shown in figures, the second electrode 315 may include theopenings 316 each of which corresponds to, i.e., surrounds, the pixelunits each having four pixels PX arranged in each row.

However, the configuration of the openings 316 should not be limited tothe above-mentioned structures. For instance, although not shown inFIGS. 7A to 7C, the second electrode 315 may include the openings 316each of which corresponds to, i.e., surrounds, the pixel units eachhaving two pixels PX arranged in each row and the openings 316 each ofwhich corresponds to the pixel units each having three pixels PXarranged in each row.

In addition, the second electrode 315 may include the openings 316 eachof which corresponds to the pixel units each having two pixels PXarranged in each row and the openings 316 each of which corresponds tothe pixel units each having m−2 pixels PX arranged in each row. In thiscase, the “m” is an integer number greater than 4 and the secondelectrode 315 may include two openings 316.

Although not shown in FIGS. 7A to 7C, the openings 316 of the secondelectrode 315 may respectively correspond to the pixel units each havingtwo or more but less than n pixels PX arranged in each row.

As shown in FIGS. 7A to 7C, the width W1 of the second electrode 315,which corresponds to the width between two openings 316 adjacent to eachother, may be smaller than the width W2 of the partition wall 314between two pixels PX adjacent to each other. However, it should not belimited thereto or thereby. As with the configuration of theelectrowetting display device 100 according to the first exemplaryembodiment, the width W1 of the second electrode 315 may be equal to thewidth W2 of the partition wall 314.

Although not shown in figures, a portion of the second fluid of theelectrowetting display device may contact the second electrode 315. Thesecond fluid has the electrical conductivity. Accordingly, the secondfluid disposed in the pixel PX may receive the common voltage Vcomthrough the second electrode 315 formed on the partition wall 314. Thatis, as described with reference to FIGS. 3A and 3B, the pixel PX may beoperated.

Consequently, because the second electrode 315 of the electrowettingdisplay device 300 according to the third exemplary embodiment includesthe openings 316, the transmittance of the light may be improved.

FIGS. 8A to 8C are plan views showing an electrowetting display deviceaccording to a fourth exemplary embodiment.

The electrowetting display device 400 according to the fourth exemplaryembodiment have the same configuration as that of the electrowettingdisplay device 200 according to the second exemplary embodiment exceptfor a configuration of openings. Accordingly, the configuration of theopenings of the electrowetting display device 400 will be mainlydescribed.

Referring to FIGS. 8A to 8C, a second electrode 415 of theelectrowetting display device 400 includes openings 416. As describedabove, the pixels PX are arranged in n rows by m columns. In addition,although not shown in FIGS. 8A to 8C, an area between the pixels PX maybe defined as a pixel boundary area. A partition wall 414 is disposed inthe pixel boundary area, and the second electrode 415 is disposed on thepartition wall 414.

Each of the openings 416 corresponds to, i.e., surrounds, pixels PXarranged in two column units and two or more row units. That is, thesecond electrode 415 is disposed on the partition wall 414 formed in thepixel boundary area between the pixel units each including the pixels PXarranged in two row units by two or more column units.

For instance, as shown in FIG. 8A, the second electrode 415 is disposedon the partition wall 414 and includes openings 416 respectivelycorresponding to, i.e., surrounding, the pixel units each including fourpixels PX arranged in two rows by two columns. That is, the secondelectrode 415 is disposed on the partition wall 414 formed in the pixelboundary area between the pixel units each including the four pixels PXarranged in two rows by two columns.

In addition, as shown in FIG. 8B, the second electrode 415 is disposedon the partition wall 414 and includes openings 416 respectivelycorresponding to, i.e., surrounding, the pixel units each including sixpixels PX arranged in two rows by three columns. That is, the secondelectrode 415 is disposed on the partition wall 414 formed in the pixelboundary area between the pixel units each including the six pixels PXarranged in two rows by three columns.

Further, as shown in FIG. 8C, the second electrode 415 is disposed onthe partition wall 414 and includes openings 416 respectivelycorresponding to the pixel units each including pixels PX arranged intwo rows by m columns. That is, the second electrode 415 is disposed onthe partition wall 414 formed in the pixel boundary area between thepixel units each including the pixels PX arranged in two rows by mcolumns. The structure shown in FIG. 8C may be called a stripestructure.

Although not shown in figures, the second electrode 415 may include theopenings 316 each of which corresponds to the pixel units each havingthe pixels PX arranged in two rows by m or more columns.

However, the configuration of the openings 416 should not be limited tothe above-mentioned structures. For instance, although not shown inFIGS. 8A to 8C, the second electrode 415 may include the openings 416each of which corresponds to the pixel units each having four pixels PXarranged in two rows by two columns and the openings 316 each of whichcorresponds to the pixel units each having six pixels PX arranged in tworows by three columns.

In addition, the second electrode 415 may include the openings 416 eachof which corresponds to the pixel units each having four pixels PXarranged in two rows by two columns and the openings 316 each of whichcorresponds to the pixel units each having pixels PX arranged in tworows by m−2 columns. In this case, the “m” is an integer number greaterthan four and the second electrode 415 may include two openings 416.

Although not shown in FIGS. 8A to 8C, the openings 416 of the secondelectrode 415 may respectively correspond to the pixel units each havingpixels PX arranged in two columns by two or more but n or less rows.

As shown in FIGS. 8A to 8C, the width W1 of the second electrode 415,which corresponds to the width between two openings 416 adjacent to eachother, may be smaller than the width W2 of the partition wall 414between two pixels PX adjacent to each other. However, it should not belimited thereto or thereby. As with the configuration of theelectrowetting display device 100 according to the first exemplaryembodiment, the width W1 of the second electrode 415 may be equal to thewidth W2 of the partition wall 414.

Although not shown in figures, a portion of the second fluid of theelectrowetting display device may make contact with the second electrode415. The second fluid is electrically conductive. Accordingly, thesecond fluid disposed in the pixel PX may receive the common voltageVcom through the second electrode 415 formed on the partition wall 414.That is, as described with reference to FIGS. 3A and 3B, the pixel PXmay be operated.

Consequently, because the second electrode 415 of the electrowettingdisplay device 400 according to the fourth exemplary embodiment includesthe openings 416, the transmittance of the light may be improved.

Although the exemplary embodiments have been described, it is understoodthat the present invention should not be limited to these exemplaryembodiments but various changes and modifications can be made by oneordinary skilled in the art within the spirit and scope of the presentdisclosure, including the claims.

What is claimed is:
 1. An electrowetting display device comprising: afirst base substrate; a plurality of first electrodes disposed on thefirst base substrate each positioned to correspond, respectively, to aposition of one of a plurality of pixels; a partition wall disposed onthe first base substrate to partition the pixels; a second electrodedisposed on the partition wall and including a plurality of openings; asecond base substrate facing the first base substrate; and anelectrowetting layer disposed between the first base substrate and thesecond base substrate, the electrowetting layer being moved by voltagesapplied to the first electrode and the second electrode.
 2. Theelectrowetting display device of claim 1, wherein the second electrodehas a width between two openings adjacent to each other equal to a widthof the partition wall between two pixels adjacent to each other.
 3. Theelectrowetting display device of claim 1, wherein the second electrodehas a width between two openings adjacent to each other smaller than awidth of the partition wall between two pixels adjacent to each other.4. The electrowetting display device of claim 1, wherein the first basesubstrate comprises a display area and a non-display area, the displayarea comprises the partition wall and the second electrode disposed onthe partition wall, and the non-display area comprises a common voltageline disposed on the first base substrate and a third electrode disposedon an outermost side surface of the partition wall to electricallyconnect the second electrode and the common voltage line.
 5. Theelectrowetting display device of claim 4, wherein the non-display areafurther comprises: an insulating layer disposed on the first basesubstrate to cover the common voltage line; and a connection electrodeelectrically connected between the third electrode and the commonvoltage line through a contact hole formed through the insulating layer.6. The electrowetting display device of claim 5, wherein the thirdelectrode has a height corresponding to a distance between an uppersurface of the insulating layer and an upper surface of the secondelectrode to make contact with the second electrode.
 7. Theelectrowetting display device of claim 4, wherein the third electrodeand the second electrode comprise a same transparent conductivematerial.
 8. The electrowetting display device of claim 4, wherein thethird electrode comprises a silver paste.
 9. The electrowetting displaydevice of claim 1, further comprising an insulating layer disposed onthe first base substrate to cover the first electrodes, and wherein thepartition wall is disposed on the insulating layer.
 10. Theelectrowetting display device of claim 9, wherein the electrowettinglayer comprises: a first fluid having at least one of an electricalnon-conductivity and a non-polarity; and a second fluid immiscible withthe first fluid and having at least one of an electrical conductivityand a polarity, and the second fluid is disposed on the insulating layerand accommodated within a space defined by the partition wall.
 11. Theelectrowetting display device of claim 10, wherein the second fluid ispolarized by a gray-scale voltage applied to the first electrodes and acommon voltage applied to the second electrode and contacts theinsulating layer to push out the first fluid to a side portion of thepixels.
 12. The electrowetting display device of claim 1, wherein theopenings are respectively positioned to correspond to the position ofthe pixels.
 13. The electrowetting display device of claim 1, whereinthe pixels are arranged in n rows by m columns, and the openings of thesecond electrode respectively correspond to pixel units each includingtwo or more but less than m pixels arranged in each row.
 14. Theelectrowetting display device of claim 13, wherein the openingsrespectively correspond to the pixel units each including two pixelsarranged in each row.
 15. The electrowetting display device of claim 13,wherein the openings respectively correspond to the pixel units eachincluding three pixels arranged in each row.
 16. The electrowettingdisplay device of claim 13, wherein the openings respectively correspondto the pixel units each including m pixels arranged in each row.
 17. Theelectrowetting display device of claim 1, wherein the pixels arearranged in n rows by m columns, and the openings of the secondelectrode respectively correspond to pixel units each including thepixels arranged in two rows by two or more, but m or less, columns. 18.The electrowetting display device of claim 17, wherein the openingsrespectively correspond to the pixel units each including four pixelsarranged in two rows by two columns.
 19. The electrowetting displaydevice of claim 17, wherein the openings respectively correspond to thepixel units each including six pixels arranged in two rows by threecolumns.
 20. The electrowetting display device of claim 19, wherein theopenings respectively correspond to the pixel units each including thepixels arranged in two rows by m columns.